Galaxies
<p>
Draw lines along grid edges so as to divide the grid up into connected
regions of squares.
<p>
Every region should have two-way rotational symmetry, should contain
exactly one dot which is in its centre, and should contain no lines
separating two of its own squares from each other. A region satisfying
all of these requirements will be automatically highlighted.
<p>
Click on a grid edge to add or remove a line. Right-click on a dot
and drag the mouse to place an arrow in a grid square pointing to
that dot, to indicate that you think that square must belong in the
same region as that dot. Right-drag an existing arrow to move it, or
drop it off the edge of the grid to remove it.
